Method of Forming Concrete

ABSTRACT

An apparatus for forming concrete includes a form having a slot configured to closely receive a plate. The slot is defined by one or more annular surfaces having central axes perpendicular to a direction in which the slot receives the plate. A method for forming same includes providing a sheet of form material; disposing a release layer on the sheet; cutting the sheet into a plurality of forms having a predetermined form height; and cutting a slot in each of each of the plurality of forms. Another apparatus for forming concrete includes a plate having a first portion and a second portion. A coating is disposed on the first portion. When disposed in a joint defined by a first volume of concrete and a second volume of concrete, the first volume of concrete adheres only to the coating and the second volume of concrete adheres only to the second portion. A method for forming concrete includes providing a plate having a coated first portion and a second portion; providing a form having a slot configured to closely receive the second portion; inserting the second portion in the slot; positioning the form to receive concrete; pouring a volume of concrete on the form and the first portion; curing the volume of concrete and defining cured concrete; and removing the form from the cured concrete. The plate remains in the cured concrete.

REFERENCE TO EARLIER APPLICATIONS

This Application is a divisional application of U.S. patent applicationSer. No. 11/077,557, filed Mar. 11, 2005, for Method of Forming Concreteand an Apparatus for Transferring Loads Between Concrete Slabs, whichclaims the benefit of and is a continuation-in-part of U.S. ProvisionalPatent Application Ser. No. 60/650,954, filed Feb. 9, 2005, for Methodof Forming Concrete and an Apparatus for Same by Stephen F. McDonald.

BACKGROUND OF THE INVENTION

Conventional concrete pavement installation involves preparing thenpositioning forms around an area intended for pavement. The forms havevertical inner surfaces to receive and contain poured concrete. Theforms have horizontal top surfaces, which typically are level with thesurface of the poured concrete, or, once cured, pavement surface. Theforms have back surfaces that rest against appropriately-spaced stakesfor holding the forms in place. To provide clearance for finishtroweling, concrete workers often field cut chamfers between the top andback surfaces of the forms.

Very large pavements require substantial form preparation andpositioning. This is especially true if stock materials for forms areshort and/or flexible. Short and flexible forms require more stakingthan longer, more rigid forms to ensure true, unwavy pavement edges.Short forms also require more setup time for chamferring. Regardless ofwhether the forms are long or short, field chamferring requiresconsiderable time for large pavement areas.

Ideally, the forms used for receiving poured concrete should have a trueheight for providing a true slab thickness. Unfortunately, forms in thefield typically have a height that is less than a true height for anappropriate slab thickness. These forms of inadequate height typicallymay be positioned so that the top surfaces are at an appropriate heightrelative to the desired pavement surface height, but present bottomsurfaces that do not contact, thus admit gaps through which pouredconcrete leaks. This wastes concrete and requires additional work toremove the excess portions.

Concrete leakage from the forms, especially at the butt joints, leavesdepressions in a finished slab surface causing poor aesthetics. Thedepressions also impair surface coverings, such as tile, because theuneven surface promotes uneven or incomplete covering layout andadhesion. Cured leaked concrete also impinges on adjacent slabs causingvoids and/or increasing the chances of obtaining a locked construction,which leads to cracks and joint failures. Finally, removing the curedexcess typically damages the slab from which the excess is chiseled.Thus, avoiding form leaks is highly desirable.

Unfortunately, none of the foregoing provides a method of formingconcrete and an apparatus for same that includes stiff, infinitely long,pre-chamferred forms with predetermined true height.

In construction of concrete pavements for highways, airport runways,large warehouse buildings and the like, preventing random cracking ofthe concrete necessitates dividing the pavement into convenient slabsections. To this end, concrete workers pour a monolithic concrete slabthat is allowed to set for a short period. Then, the workers cuttransverse grooves, having a depth on the order of one-fourth of theslab thickness, across the slab, with spacing between cuts selected inaccordance with the application and design. Spacings from 12 to 40 feetare common for highway pavements.

As the concrete of the slab cures, forces derived from the exothermalcuring reactions cause generally vertical cracks to develop through theslab thickness at the reduced cross-sections below each groove. Thiscontrolled cracking effectively divides the slab into predeterminedseparate slab sections.

The vertical cracks or joints define adjacent and interlocking facesformed by the cement and aggregates in the concrete. The interlockingfaces transfer vertical shear stresses among adjacent slab sections, aphenomenon commonly referred to as “aggregate interlock,” as heavyobjects, such as motor vehicles, pass over the joint.

Aggregate interlock causes wear among slab intersections with increasinguse of the pavement. Additionally, cyclical and extreme temperaturechanges decrease slab volumes. Thus, over time, as traffic continuouslypasses over a joint, the intersections wear and become smooth, then failaltogether, resulting in relative vertical displacement of adjacent slabsections, hence a rough pavement surface. Joint failure also becomesincreasingly susceptible to water intrusion, which may freeze and causedamage among adjacent slabs.

To discourage relative vertical displacement among adjacent slabs, priorart techniques provide for implanting dowels in concrete extendingacross the joint intersections. Some dowels are smooth steel rods withdiameters on the order of one inch and lengths of two feet. Each rod iscoated or otherwise treated so that it will not bond to concrete alongits length or at least on one end thereof. Thus, as a slab expands andcontracts during curing and subsequently with temperature changes, thedowel is free to move horizontally relative to, yet maintain verticalalignment of adjacent slabs, augmenting the aggregate interlock totransfer vertical shear stresses across the joints. See, for example,U.S. Pat. No. 3,397,626, issued Aug. 20, 1968, to J. B. Kornick et al.for Plastic Coated Dowel Bar for Concrete and U.S. Pat. No. 4,449,844,issued May 22, 1984, to T. J. Larsen for Dowel for Pavement Joints.

Among other problems, the foregoing techniques involve significant timeand labor to produce and place the dowels.

Another technique to discourage relative vertical displacement amongadjacent slabs involves embedding square-shaped load plates in adjacentslabs with opposed corners of the load plate aligned with the joint. Toavoid shrink- or thermally-induced stress creation between the plate anda slab, concrete workers first embed a blockout sheath in one verticaljoint face for receiving a load plate. To this end, the workers nailonto a form a mounting plate, from which a blockout sheath extends, thenposition the form to receive poured concrete. Once the concrete is curedand bonded to the blockout sheath, the workers remove the form board andleave the blockout sheath in place. Then the workers insert a load plateinto the blockout sheath. Finally, the workers pour an adjacent slab,which bonds to the exposed portion of the load plate. See, for example,U.S. Pat. No. 6,354,760, issued Mar. 12, 2002, to Boxall et al., forSystem for Transferring Loads Between Cast-in-Place Slabs.

Drawbacks of the foregoing include the cost and labor associated withproducing separate mounting and load plates, then assembling samefollowing curing of a first concrete slab.

Unfortunately, none of the foregoing provide a method of formingconcrete and an apparatus for same that includes partially coated loadplates carried in slotted forms.

What are needed, and not taught or suggested in the art, are a method offorming concrete and an apparatus for same that provide partially coatedload plates carried in slotted, stiff, infinitely long, pre-chamferredforms with predetermined true height.

SUMMARY OF THE INVENTION

The invention overcomes the disadvantages noted above by providing amethod of forming concrete and an apparatus for same that providepartially coated load plates carried in slotted, stiff, infinitely long,pre-chamferred forms with predetermined true height. An embodimentconfigured according to principles of the invention includes a formhaving a slot configured to closely receive a plate. The slot is definedby one or more annular surfaces having central axes perpendicular to adirection in which the slot receives the plate.

Another embodiment configured according to principles of the inventionincludes providing a sheet of form material; disposing a release layeron the sheet; cutting the sheet into a plurality of forms having apredetermined form height; and cutting a slot in each of each of theplurality of forms.

A further embodiment configured according to principles of the inventionincludes a plate having a first portion and a second portion. A coatingis disposed on the first portion. When disposed in a joint defined by afirst volume of concrete and a second volume of concrete, the firstvolume of concrete adheres only to the coating and the second volume ofconcrete adheres only to the second portion.

Yet another embodiment configured according to principles of theinvention includes providing a plate having a coated first portion and asecond portion; providing a form having a slot configured to closelyreceive the second portion; inserting the second portion in the slot;positioning the form to receive concrete; pouring a volume of concreteon the form and the first portion; curing the volume of concrete anddefining cured concrete; and removing the form from the cured concrete.The plate remains in the cured concrete.

The invention provides improved elements and arrangements thereof, forthe purposes described, which are inexpensive, dependable and effectivein accomplishing intended purposes of the invention.

Other features and advantages of the invention will become apparent fromthe following description of the preferred embodiments, which refers tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail below with reference to thefollowing figures, throughout which similar reference characters denotecorresponding features consistently, wherein:

FIG. 1 is an environmental perspective view of an embodiment of anapparatus for forming concrete configured according to principles of theinvention shown adjacent to concrete;

FIG. 2 is a top front right side elevational view of another embodimentof an apparatus for forming concrete configured according to principlesof the invention;

FIG. 3 is cross-sectional detail view, drawn along line 3-3 in FIG. 2;

FIG. 4 is a plan view of a plate of the embodiment of FIG. 2;

FIG. 5 is a schematic view of an embodiment of a method of making anapparatus for forming concrete configured according to principles of theinvention;

FIG. 6 is a schematic view of an embodiment of a method of formingconcrete configured according to principles of the invention; and

FIG. 7 is a plan view of another embodiment of an apparatus for formingconcrete configured according to principles of the invention, shownpartially in cross-section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention is a method of forming concrete and an apparatus for samethat provide partially coated load plates carried in slotted, stiff,infinitely long, pre-chamferred forms with predetermined true height.

Referring to FIG. 1, an embodiment of an apparatus for forming concreteconfigured according to principles of the invention includes a form 100.Form 100 has a side surface 105, a top surface 110, a back surface 115and a bottom surface 120. Side surface 105 and back surface 115 define awidth 125 ranging from 0.875 to 2.500 inches. Top surface 110 and bottomsurface 120 define a height 130 ranging from 3 to 18 inches or more,depending on the thickness required for pavement.

Form 100 has a chamfer 135 between top surface 110 and back surface 115.Chamfer 135 defines an angle 140 relative to top surface 110 rangingfrom 10° to 89°, preferably 22.5° to 45°. Side surface 105 and chamfer135 define a top surface width 143 ranging from 0.125 to 0.875 inch.Chamfer 135 provides clearance for trowels and other finishing tools andallows for faster concrete finishing.

Width 125, height 130, angle 140 and top surface width 143 vary asneeded to provide a desired overall stiffness of form 100. Formstiffness dictates the amount of staking required to maintain form 100in place against the great weight of poured concrete 155. Stiffer forms100 require less staking, thus less labor to place forms 100 whereneeded.

More importantly, form stiffness impacts the trueness of an edge 145defined by side surface 105 and top surface 110, which forms acorresponding edge in concrete 155 when cured. Good trueness isimportant to the overall appearance of a pavement defined by multipleslabs having adjacent edges. For example, if an edge of one slab haspoor trueness and is adjacent to another slab edge that has poortrueness, the gap defined between the un-true edges will exhibitunsightly non-uniformity, or portions of the gap that may be too narrowfollowed by portions that may be too wide. This gap non-uniformitycontributes to an overall non-professional image of the area andassociated business.

Preferably, form 100 is constructed of oriented strand board (OSB). OSBstock may be manufactured to assume virtually any dimension, which maybe machined, as described below, to define forms 100 of virtually anylength. As the invention is intended for constructing large-scalepavements, forms 100 with very large lengths are desirable because fewerabutting forms 100 are needed to define a continuous side surface 105and edge 145, hence slab side. This reduces the labor needed to limitand/or treat discontinuities that may occur in the slab side. OSB stockalso is preferred because it may be machined to define a desired height130. This eliminates the occurrence of concrete leaks between the bottomsurface of prior art forms of inadequate height and the supportingsurface underlying the concrete.

Form 100 also may be constructed of dimensional lumber, particle board,metal, plastic, cardboard, fiber board, polyurethane foam, Styrofoam®,or other rigid synthetic or other suitable materials commensurate withthe purposes described herein.

A release overlay 160 is disposed on side surface 105. Release overlay160 is constructed of phenolic paper, kraft paper, acrylic, latex,melamine, Formica®, foil, oil, high density overlay, metal or othersuitable material that provides a smooth, closed-celled surface,substantially free of pores for retaining poured concrete withoutadhering to or marring the finished surface thereof when cured andseparated from form 100.

Referring to FIG. 2, another embodiment of an apparatus for formingconcrete configured according to principles of the invention includes aform 200 and one or more plates 300 received in form 200. Form 200 isconstructed similarly to form 100 and has slots 260 for receiving plates300. Slots 260 have a spacing 261 of about two feet, or other dimensionsuitable for purposes described herein.

Referring also to FIG. 3, each slot 260, preferably, is formed by plungecutting with a rotary saw blade (not shown). Slot 260 is defined byannular surfaces 263, each having curvatures corresponding to the radiusof the plunge-cutting saw blade. Annular surfaces 263 and side surface205 (comparable to side surface 105 of form 100) define opposed proximalintersections 265. Annular surfaces 263 and back surface 215 (comparableto back surface 115 of form 100) define opposed distal intersections270.

Referring also to FIG. 4, each plate 300, preferably is constructed ofsteel or any material suitable for performing as a load transfer devicebetween adjacent concrete slabs in a pavement. To economize productioncosts, plate 300 may be shear-cut. Plate 300 is 0.250-0.375 inches thickand has a side dimensions 303 of approximately 4.5 inches, or otherdimension suitable for purposes described herein. Preferably, plate 300has a length 305 that is greater than or equal to a width 310. Thus,plate 300, in plan view, assumes the shape of a rhombus or square. Platemay be constructed as set forth in U.S. Pat. No. 6,354,760.

Plate 300 has a first portion 315 and a second portion 320, delineatedby a plane 321 defined by the intersections of sides 322 and 323 thatare aligned with side surface 205. First portion 315 may be untreated.Second portion 320 has an elastomer coating 325 configured to adhere toconcrete, but not to plate 300. Elastomer coating 325 is constructed ofpolymers, grease or other materials suitable for the purposes describedherein.

In practice, when a first concrete slab adheres to elastomer coating 325on second portion 320 and a second concrete slab adheres to firstportion 315, lateral movement among the slabs, due to shrinkage, etc.,will not cause localized stresses because the first and second slabs arenot fixed to plate 300, rather, one slab is permitted to move relativeto plate 300 because it is adhered to elastomer coating 325. Whileelastomer coating 325 originally adheres to plate 300 when plate 300 ismanufactured, curing concrete exerts forces on elastomer coating 325which urges elastomer coating 325 to slide relative to plate 300 onceinstalled.

Alternative embodiments of the invention include coatings that: (1)adhere to plate 300, but not to concrete, thereby allowing concrete toslide relative to the coating; or (2) do not adhere to plate 300 orconcrete, thereby allowing concrete to slide relative to plate 300and/or the coating.

Referring again to FIG. 2, first portion 315 is received in slot 260.Preferably, slot 260 has a tolerance of 0.03125 inch among horizontalsurfaces of slot 260 and first portion 315. This close tolerancingpromotes closely receiving first portion 315 in slot 260. This providesfor maintaining plate 300 at a desired attitude. Elastomer coating 325is likely to have a thickness exceeding this tolerance that wouldprevent slot 260 from receiving second portion 320.

Referring also to FIG. 3, plate 300 is configured such thatintersections of sides 322 and 323 at the widest extremes of plate 300mate with proximal intersections 265 of form 200. This configurationpromotes a gap-free junction between plate 300 and form 200 thatdiscourages concrete from seeping therethrough. This ensures thatconcrete only contacts elastomer coating 325 and not plate 300.

Plate 300 also is configured, and the radius of a saw (not shown) usedfor plunge cutting slot 260 is selected, such that distal intersections270 in form 200 firmly cradle first portion 315. This configurationprevents plate 300 from undesired rotation or movement relative to form200 despite significant forces exerted on plate 300 by concrete whenpoured on form 200 and plate 300.

Referring to FIG. 7, another embodiment of a plate 700 configuredaccording to principles of the invention has a first portion 715 and asecond portion 720, delineated by a plane 721. First portion 715 may beuntreated. Second portion 720 has an elastomer coating 725 that issimilar to elastomer coating 325.

In practice, first portion 715 is received in a slot 860 in a form 800in a direction aligned with a side 730 extending along first portion 715and second portion 720. Coating 725, having a preferred thickness ofabout 0.03 inches and being compressible, allows a cured slab (notshown) adhered thereto to move somewhat relative to second portion 720.

Referring to FIG. 5, an embodiment of a method 400 configured accordingto principles of the invention includes: a step 405 of providing asheet; a step 410 of disposing a release overlay on the sheet; a step415 of cutting the sheet into a plurality of forms; and a step 420 ofcutting a chamfer in each of the plurality of forms.

Step 405 of providing a sheet of material includes material suitable forperforming as a concrete form, preferably OSB stock material. However,the material may be dimensioned lumber, particle board, steel and othersuitable materials if commensurate with the purposes described herein.OSB material is preferred because it can assume virtually any width,length or thickness that may be machined into forms of appropriate, truedimensions for defining the desired pavement. The length of thematerial, ideally, should be as long as the longest side of the pavementdesired. However, manufacturing material that is, e.g. two miles long,is problematic for contemporary manufacturers.

Step 410 of disposing a release overlay on the sheet includes an overlaythat is suitable for retaining poured concrete without adhering theretoor marring the finished surface thereof when the concrete cures and isseparated from the form.

Step 415 of cutting the sheet into a plurality of forms ties into step405 in that the material to be cut should be selected to maximize thenumber of forms machined and minimize any scrap not suitable to be aform. The number of forms derived from the sheet depends on thethickness of pavement desired, which dictates the height of the formsneeded. Ideally, the width of the sheet of material provided in step 405should be an even multiple of the form height, plus some allowance forcutting.

Step 420 of cutting a chamfer in each of the plurality of forms involvesmachining each form derived from step 415 with a chamfer machine thatcuts chamfers in board stock. The chamfer may assume any angle suitablefor purposes described herein, but preferably ranges from 22° to 45°.Step 420 provides tremendous labor savings over prior art techniques andmaterials. Ordinarily, concrete workers field cut chamfers into concreteforms on site, which consumes considerable time. Providing workers withpre-chamfered forms eliminates this on-site step and allows for fastercompletion of the paving job at hand.

Referring to FIG. 6, an embodiment of another method 500 configuredaccording to principles of the invention includes: a step 505 ofproviding a plate with a plate coating disposed on a first portionthereof; a step 510 of providing a form having a slot configured receivea second portion of the plate; a step 515 of inserting the secondportion in the slot; a step 520 of positioning the form to receiveconcrete; a step 525 of pouring a volume of concrete against the formand the first portion; a step 530 of curing the volume of concrete anddefining cured concrete; and a step 535 of removing the form from thecured concrete, wherein the plate remains in the cured concrete.

Step 505 of providing a plate with a plate coating disposed on a firstportion thereof involves preparing a plate 300 as described above. Anelastomer coating, configured to adhere to concrete, but not to theplate, is disposed on the first portion of a plate.

Step 510 of providing a form having a slot configured receive a secondportion of the plate involves plunge cutting the side surface of a formwith a rotary blade having a pre-determined radius selected according tothe configuration of the plate received in the slot, as described above.

Step 515 of inserting the second portion in the slot represents asignificant cost savings over prior load plate installation apparatusesand methods. Rather than attaching to a form a mounting plate andblockout sheath, then, after the slab has cured, removing the form whilebreaking free the blockout sheath followed by inserting a load plate inthe blockout sheath, the present method embeds a load plate directlyinto the concrete slab as it cures. Once the concrete cures, the formsare removed with the load plate already embedded in the concrete and nofurther installation required.

Step 520 of positioning the form for receiving concrete also representsan advance over many typical concrete pouring techniques in use. Becausethe forms are precisely cut prior to being staked around the desiredpavement area, they present a true height from support surface topavement surface. This deters concrete from leaking through any gap thatoften exists between the support surface and the bottom surface ofinadequately sized prior art forms.

Step 525 of pouring a volume of concrete against the form and the firstportion and step 530 of curing the volume of concrete and defining curedconcrete are conventional, thus described no further.

Step 535 of removing the form from the cured concrete wherein the plateremains in the cured concrete, as described above, represents asignificant departure from current practices. Once the concrete cures,the forms are removed with the load plate already embedded in theconcrete. Other methods require detaching a form from a mounting platepreviously attached thereto, then installing a load plate in the pocketformed in the concrete.

The invention is not limited to the particular embodiments described anddepicted herein, rather only to the following claims.

1. Method of forming concrete comprising: providing a plate having acoated first portion and a second portion; providing a form having aslot configured to closely receive the second portion; inserting thesecond portion in the slot; positioning the form to receive concrete;pouring a volume of concrete on the form and the first portion; curingthe volume of concrete and defining cured concrete; and removing theform from the cured concrete; wherein the plate remains in the curedconcrete.
 2. Method of claim 1, further comprising: pouring a secondvolume of concrete adjacent to the cured concrete and on the secondportion; and curing the second volume of concrete and defining a secondcured concrete.